Rihanna sat courtside with friends for CC Sabathia's and Robinson Cano's Summer Classic Charity basketball game on Thursday at the Barclays Center in Brooklyn where she ran into her ex-boyfriend Chris Brown, who was playing in the game.

Rihanna Reunites With Chris Brown At Charity Game

Rihanna, who was at the event with a group of friends that included British model Cara Delevingne, apparently wasn’t aware that Brown would be playing in the game prior to making arrangements to attend.

“Chris wasn't scheduled to play in the game," a source told to E! News. "[Shawn] Pecas asked him to and he was all about it. Rihanna had already promised so this forced them to be in the same place at the same time."

"Chris was showing off the entire game," the insider added. "They didn't speak to each other at all."

During the game, Rihanna, dressed in cut off jeans and an oversized Run DMC sweatshirt, looked less than impressed with her ex-boyfriend’s basketball skills. When the “Turn Up the Music” singer slapped the hands of some children sitting in front of the “Diamond” singer’s seats, she appeared to purposefully look off in the other direction.

While Rihanna is rumored to have reunited with rapper Drake, Brown appears to be back on with his on-off girlfriend Karrueche Tran. The night prior to the charity game, Brown brought Tran to the USA vs Dominican Republic basketball game at Madison Square Garden. That same day Brown posted a picture of Tran on his Instagram and sparked baby rumors, writing, “damn near 5 years and this woman still putting up with my s–t. Need to have this baby and stop playing! Lol! My WCW.”

Brown and Rihanna dated for a couple of years before splitting in 2009 after the infamous assault prior to the 51st Annual Grammy Awards. The two briefly rekindled their romance in 2013 before breaking things off once again.